gnucash maint: Fix test failure for timezones west of the prime meridian.

[John Ralls]

Updated	 via  https://github.com/Gnucash/gnucash/commit/6a3fabc3 (commit)
	from  https://github.com/Gnucash/gnucash/commit/ca9d58b2 (commit)



commit 6a3fabc30d8e0f551c8918703f07119d5f5bb065
Author: John Ralls <jralls at ceridwen.us>
Date:   Sat May 2 15:29:02 2020 -0700

    Fix test failure for timezones west of the prime meridian.
    
    The previous fix didn't calculate the comparison time correctly and
    ended up in the wrong day because the GMT time is before the local time.
    
    In the course of checking the corner-case timezones (Midway and
    Kiritimati) I found an error in the GncDateTime calculation of the
    neutral time, so fixed that too.



Summary of changes:
 bindings/python/tests/test_business.py | 13 ++++++++++---
 libgnucash/engine/gnc-datetime.cpp     |  2 +-
 2 files changed, 11 insertions(+), 4 deletions(-)